"I think because there is a lot of interest out there and there are some commercial companies trying to solve the problem," she says.

"In the next three or four years it should be on the computer of everyone who is a music fanatic."

Uitdenbogerd says one form of retrieving audio by singing will involve users calling up a specific website then singing a tune or lyrics into a computer microphone to submit their query.

The computer will then search the website's database to retrieve a menu of digital files, which the user can then choose from to download.

But the quality of your voice will affect the search.

"The more in tune and accurate you are the less you will have to sing," Uitdenbogerd says, because the computer will recognise the notes more easily.

And the more out of tune you are the longer you will have to sing.

But no matter how bad your voice "most people can get the ups and downs" of a tune "in the right place", she says.

The flaw in current text-based music searches is that lyrics might not be unique and in some cases, such as in classical music, nonexistent.

Background noise

Main hurdles programming must overcome is the diversity of music and the effect interference from things such as sound quality and environmental noise have on the ability of the program to detect notes.

These outside influences can affect the frequency of the notes the program is trying to interpret.

"Audio is just a wave form that goes up and down and doesn't bear much resemblance to how we perceive [music] as notes," she says.

She says music can be monophonic with only note played at a time or polyphonic, where a number of notes are happening at the same time, for example in rock and classical music.

Uitdenbogerd says it is easier to solve the retrieval problems by focusing on just one genre of music, for instance operatic arias.

But there is a concern that this can lead to retrieval systems that only work with a limited range of music.

Uitdenbogerd's team is also looking at audio searches by instrument timbre and by mood.

She says if someone wants music with a "fat bass sound" that can be used as the main criteria for the search and the mood search will be based on predicting what mood the music conveys.